rails多对多

背景：
明星和管理员，多对多

classAdmin<ActiveRecord::Base
has_and_belongs_to_many:stars
end

classStar<ActiveRecord::Base
......
has_and_belongs_to_many:admins

......
end

共有3个表：admins,stars,admins_stars,关联表admins_stars只有两个字段：star_id,admin_id

以一个测试用例作为说明

开头：

requireFile.dirname(__FILE__)+'/../test_helper'

classAdminTest<Test::Unit::TestCase
fixtures:admins,:agents,:stars,:admins_stars

defsetup

@admin=Admin.find(1)
end
....

测试读：

deftest_read
assert_equal1,@admin.id
assert_equal"1",@admin.nick_name

assert_equal2,@admin.stars.length

assert_equal"谭咏麟",@admin.stars[0].name_cn
end

测试新增：

deftest_create

new_admin=Admin.new
new_admin.login_name="aa"
new_admin.nick_name="bb"
new_admin.star_ids=[2,3]

new_admin.save

new_admin=Admin.find(new_admin.id)

assert_equal2,new_admin.stars.length

end

测试修改：

def test_update

assert_equal 2,@admin.stars.length
assert_equal 1,@admin.stars[0].id
assert_equal 2,@admin.stars[1].id

@admin.star_ids=[3]

@admin.nick_name="aa"

@admin.save


@admin = Admin.find(1)
assert_equal 1,@admin.stars.length
assert_equal 3,@admin.stars[0].id

end

测试删除：

deftest_delete
assert_equal4,Admin.find(:all).length

Admin.destroy[1,2]
assert_equal2,Admin.find(:all).length
end

注意：
Admin.destroy[1,2]是一条条删除纪录
Admin.delete[1,2]批量删除，但在本例中会违反外键约束，delete看来比较适合独立的表的批量删除